An international team of researchers has discovered a mysterious ancient city on top of a hill in central Greece.

Scattered on and around the Strongilovoúni hill on the great Thessalian plains near a village called Vlochós, some 190 miles north of Athens, the ruins had been dismissed as part of a small, irrelevant settlement.

"The fact that nobody had ever explored the hill before is a mystery," Robin Rönnlund, a PhD student in Classical Archaeology and Ancient History at the University of Gothenburg and leader of the fieldwork, said.

Rönnlund and colleagues from the University of Bournemouth, completed the first field season during two weeks in September 2016. The work was done in collaboration with the Swedish Institute at Athens and the local archaeological service in Karditsa.

Fragment of red-figure pottery from the late 6th century BC, probably by Attic painter Paseas. Credit: SIA/EFAK/YPPOA

Ancient pottery and coins unearthed by the archaeologists helped date the city to at least 2,500 years ago.

"Our oldest finds are from around 500 BC, but the city seems to have flourished mainly from the fourth to the third century BC before it was abandoned for some reason, maybe in connection with the Roman conquest of the area," Rönnlund said.

The researchers hope to avoid traditional excavation and plan to use ground-penetration radar instead. The technology will enable the team to leave the site in the same shape as it was in when they arrived.